#main{

    width: 100px;
    height: 100px;
    background: RGB(125,25,264);
    font-size: 80px;


}
@media screen and (min-width: 500px)  and (max-device-width: 1800px){
    #main{
        width:500px;
        height:500px;
        background: RGB(25,245,25);
    }
}